Fig. 9

Mechanism by which RE NMs promote angiogenesis.A Atomistic models and (oxygen) electrostatic energy surfaces for CeO NPs. Sphere model representation of the atomic positions comprising (a) the unreduced CeO NPs and (b) the reduced CeO NPs. Oxygen is coloured red, Ce⁴⁺ is white, and Ce³⁺ is blue. (c) and (d) show the electrostatic energy surface maps of the unreduced and reduced CeO NPs, respectively, and enlarged views are shown in (e) and (f), respectively. (g) and (h) show an area of a CeO NP with a high concentration of Ce³⁺ (yellow spheres) on the surface. Domains near Ce³⁺ are red, indicating labile oxygen; conversely, domains relatively devoid of surface Ce³⁺ are blue, indicating reduced oxygen extraction reactivity. Source: Reprinted from ref. [182] , copyright 2024, with permission from Elsevier. B (a) Primary cell culture with 1 μg/mL nanoparticles and 1000 units/mL catalase. (i) Blank control, (ii) 1000 units/mL catalase, (iii) 20 ng/mL VEGF, (iv) 20 ng/mL VEGF and 1000 units/ml catalase, (v) 1 μg/mL Eu rods, (vi) 1 μg/mL Eu rods and 1000 units/mL catalase. (b) Quantitative analysis showing that catalase can abolish proangiogenic activities induced by nanoparticles but not by VEGF. Source: Reprinted from ref. [188] , copyright 2024, with permission from WILEY. C Western blot analysis showing greater levels of Ref-1/APE1, HIF-1α, and VEGFA in the 0.6 mg CNP group than in the PBS-only group at days 3 and 7. Source: Reprinted with permission from ref D Enhanced NO production by EHNs. Fluorescence imaging of nitric oxide production in EA: hy926 cells incubated with (a, a1) nothing (control) or (b, b1) EHNs (5 μg/mL). Source: Reprinted from ref with permission of the Royal Society of Chemistry, 2024; permission conveyed through the Copyright Clearance Center, Inc. Ref-1/APE1, apurinic/apyrimidimic endonuclease 1/ redox factor 1; HIF-1α, hypoxia-inducible factor 1 alpha; VEGFA, vascular endothelial growth factor A; CNP, cerium oxide nanoparticles; EHNs, europium hydroxide Eu(OH)₃ nanorods